1. Field of the Invention
The present invention relates to a tunnelling device for use in forming an anatomical tunnel within which is to be received a cardiovascular graft during reconstructive peripheral vascular surgery. More specifically, the invention relates to a tunnelling device which is a combined tunneller, graft introducing device and temporary conduit for use in the placement of a vascular graft within tissue prior to the fixation of the graft to an existing peripheral vessel to form a bypass around a vessel or portion thereof.
2. Description of the Prior Art
When performing peripheral vascular reconstructive procedures, it is a common practice to create a subcutaneous or anatomic tunnel between anastomotic sites for passage of a graft therethrough. The graft may be of autogenous, synthetic or biological origin.
Synthetic grafts are relatively durable and may be pulled through an anatomic tunnel without damage. However, grafts of biological origin are relatively fragile, whether autografts, heterografts or homografts, and can tear if pulled through an antomic tunnel. To minimize chances of tearing of the graft due to inherent friction between the graft and surrounding tissue, surgeons have provided a conduit, such as a disposable chest tube container, around the tunnelling device for the formation of a subcutaneous conduit through which the graft is to be passed once the tunnelling device is removed. After the graft is fed through the conduit forming container, the container is removed with the graft remaining in the anatomic tunnel.
Various prior art devices have been proposed for assisting the passage of a tubular element through body tissue. Examples of some of these devices are disclosed in the following U.S. Patents:
______________________________________ U.S. Pat. No. PATENTEE ______________________________________ 3,710,777 Sparks 3,866,247 Sparks 3,866,609 Sparks 3,999,551 Spitz et al. 4,327,722 Groshong et al. 4,418,693 Leveen et al. 4,431,426 Groshong et al. 4,432,752 Marlon ______________________________________
The Sparks U.S. Pat. No. 3,710,777 discloses a slightly bent metal tunnelling tube containing a flexible plastic core rod which closes off the distal end of the tube with a plug provided on the rod. Once the tunnelling tube and core rod have been placed in a thigh of a patient, the core rod is removed. A mandrel assembly with a coarse mesh fabric coating is inserted into the tunnelling tube. The tunnelling tube is then removed, leaving the mandrel assembly in place, around which a graft is grown.
The Sparks U.S. Pat. Nos. 3,866,247 and 3,866,609 disclose a similar tunnelling tube for different processes of graft formation.
The Spitz et al. U.S. Pat. No. 3,999,551 discloses a subcutaneous guide assembly comprising an elongated rod of predetermined contour and length which has a handle on one end and to the other end of which a variety of surgical elements can be threadedly engaged. In use, the assembly is inserted into one incision and then the distal end is caused to exit a second incision. At that time, the surgical element is attached to the distal end and pulled back into the body for implantation of the device.
The Groshong et al. U.S. Pat. Nos. 4,327,722 and 4,431,426 disclose apparatus for intravenous therapy such as total parenteral provision of nourishment. For long term use, a passer for a catheter of the assembly is provided which passer comprises a sharp tipped elongate tube.
The LeVeen et al. U.S. Pat. No. 4,418,693 discloses a vein and tubing passer. The passer comprises inner and outer slidable tubular members. One is flexible and the other is rigid. Once placed, the rigid member is withdrawn and a grafting element is attached to the flexible member which pulls the grafting element through the body tissue to the desired location.
The Marlon U.S. Pat. No. 4,432,752 discloses a procedure for inserting indwelling catheters. A larger catheter is utilized to provide a tunnel for a smaller catheter.
As will be described in greater detail hereinafter, the tunnelling device of the present invention differs from the previously proposed devices by providing in a single unit, all the elements necessary for the atraumatic placement of a graft within an anatomic tunnel thereby to minimize the possibility of damage to the graft.